Reclassification of the carbon footprint of electric and internal combustion engine passenger cars by the ICCT

The European Union’s “Green Deal” aims to achieve climate neutrality in Europe by 2050. To achieve this goal, greenhouse gas emissions (GHG) from the transport sector must be reduced by at least 90% compared to 1990 levels. With this in mind, the ICCT (International Council On Clean Transportation) has conducted a new study to determine which combination of powertrain technologies and fuels can be used to reduce greenhouse gas emissions from passenger cars to a minimum – not only direct emissions from the tailpipe, but also indirect emissions from fuel and electricity production, as well as vehicle and battery manufacturing.

As part of the ICCT study, a life cycle analysis (LCA) of various passenger car propulsion systems and fuel types was conducted with respect to their GHG emissions. It includes internal combustion engine vehicles (ICEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), and fuel cell vehicles (FCEVs) – as well as a variety of fuel types and energy sources, including fossil gasoline, diesel, and natural gas, each with the current and future share of biofuels or biomethane blends, e-fuels, hydrogen, and electricity. The assessment presented here for passenger cars in Europe is part of this global LCA study, which also includes India, China, and the United States. The same trends are observed for each of the four regions.

Figure 1: Life-cycle GHG emissions of lower medium segment gasoline, diesel, and CNG ICEVs, PHEVs, BEVs, and FCEVs registered in Europe in 2021 (Source: ICCT)

Conventional gasoline and diesel vehicles have very similar emissions. In the case of hybrid vehicles, emissions are about 20% lower. In the case of compressed natural gas (CNG) vehicles, emissions can even exceed those of gasoline and diesel vehicles.
The addition of biofuel, which is common in Europe, hardly reduces emissions from gasoline, diesel, and CNG vehicles – even if biofuels from waste- and residue-based feedstocks were to displace the currently much-used palm oil by 2030. Synthetic fuels (e-fuels) involve very high production costs and therefore cannot contribute significantly to decarbonizing the road transport fuel mix.
In real everyday operation, the fuel consumption of PHEVs is in many cases higher than in the official consumption figures. The life cycle emissions of today’s PHEVs in the compact class are therefore only about 25-27% lower than those of new gasoline vehicles.
The lifecycle emissions of new BEVs registered in Europe in the compact class are already 66%-69% lower than for comparable new gasoline cars. Due to the steadily improving electricity mix, this emissions advantage of BEVs for new vehicles increases to about 74%- 77% in 2030. Provided they are powered entirely by renewable electricity, BEVs achieve up to 81% lower lifecycle emissions than gasoline vehicles.
GHG emissions from the production of batteries used in BEVs and PHEVs are calculated using regionally adjusted GHG emission factors in kg CO2 eq./kWh and the respective battery capacities in kWh. For current 2021 and 2030 forecast, this study considers the battery technology development of recent years. The study is based on battery production data available in 2021, current state-of-the-art battery chemistry, and regional shares of local battery production vs. imports. Together, these factors result in a significantly lower carbon intensity for battery production than previous studies. Estimated GHG emissions from battery production for BEVs are equivalent to those from hydrogen system production in FCEVs, accounting for only about one-third of total BEV production emissions.
For FCEVs, lifecycle emissions vary greatly with the hydrogen used. For the predominant hydrogen used today, which is produced by reforming methane from natural gas (“gray hydrogen“), GHG emissions are about 26% lower than for new gasoline vehicles. In contrast, for hydrogen produced from renewable sources (“green hydrogen“), emissions are 76% lower than gasoline vehicles. FCEVs powered by renewable hydrogen have slightly higher life-cycle emissions than BEVs using the same renewable electricity. This is because of the conversion of electricity to hydrogen and back to electricity, which is about three times more energy intensive than using the electricity directly in BEVs.
The analysis for renewables also considers emissions from building additional wind turbines and solar panels.

Based on the analysis, the ICCT recommends clear actions to achieve the European decarbonization targets for 2050:

Registration of new ICE passenger cars in the EU should be phased out in the 2030-2035 timeframe. Given an average vehicle lifetime of 18 years, only technologies that can achieve deep decarbonization of the European car fleet by 2050 should be produced and registered starting around 2030-2035. BEVs powered by electricity from renewable sources and FCEVs powered by green hydrogen are the only two technology paths that can be considered for this purpose. Hybridization of internal combustion engines can be used to reduce the fuel consumption of new vehicles registered over the next decade, but neither HEVs nor PHEVs will allow the long-term reductions in GHG emissions from passenger cars that are needed.

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